As part of its new power accessory line for Apple's iOS devices, Mipow has released two battery cases for the iPhone 4: the oddly-named Clone ($69) and Maca Air Color ($79). The cases are somewhat similar in form but vary in finish, size, and power capacity. Despite the similar appearances, overall performance is drastically different between the two models.

Clone is the thicker of the two cases. It’s composed of a matte black plastic backplate with clear sides and a removable top cap—two are included in the package in case one gets lost. The cap stays on pretty securely; to remove it, you must pull on the case’s backing and lift up. All of the buttons and ports are left fully exposed, with the exception of the Dock Connector port, which fits on top of the charging plug. On the front of the case there are two metal grill-covered openings—one for the speaker and the other for the microphone—and on the bottom there’s a Micro USB port for charging the battery and the iPhone 4. It’s not the best looking design we’ve ever seen, but it’s not bad.

Along the bottom of the back of the case are a power button and four capacity lights; quickly pressing and releasing the power button shows how much charge there is in the case, although we found that the lights didn’t give a very good representation of the actual charge. A dedicated power switch would have been better, as the dual functionality of the button can be confusing. The thing that makes Clone a little bit different than competing models is the fact that the power source is removable. Directly above the button and lights is a cover that slides off. Removing it reveals a 1500mAh Nokia BP-4L-style battery that is made to be swappable—the company even sells a spare battery and wall charger kit, and you can get these battery packs at other stores for $12 and up, depending on the quality you want. This is a potentially great feature for those who travel or may otherwise be away from power for long periods of time.

The iPhone 4 has a roughly 1400mAh capacity battery—1420mAh, it’s claims—though since some power is naturally lost in the transferring process, we wouldn’t expect Clone to provide a complete charge. It actually performed very closely to a case we have recommended in the past, Mophie’s Juice Pack Air. In both instances we tested a powered-on, 3G/Wi-Fi-connected iPhone 4 with the screen turned off, no calls coming in, and no audio playing. Clone provided a 71% increase in battery life, going from 12% to 83% in a little under two hours. The charging period is one of the problems with Clone: while the iPhone 4 can accept a full 1A charge, Mipow’s case is only 0.5A—this means that it charges at half speed, also an issue with Juice Pack Air.

Maca Air Color is almost identical to Clone on its front and sides. Instead of a removable plastic back, however, it has a fixed metal one. Many people will like the bright, radiating design, available in light blue, charcoal gray, gold, green, navy blue, purple, black, or red. Other than appearance, the other major difference is that the case is noticeably thinner due to a lower-capacity 1200mAh battery. It’s actually pretty impressive just how slim the battery is. Just as with Clone, there are a button and lights at the bottom of the back of the case.

Unfortunately Maca Air Color sacrifices functionality for its form. The charging ability of the case is significantly less than that of Clone—a steeper fall than might have been expected on rated capacity alone. In testing, the battery brought an iPhone 4 from 9% to 51% in just over an hour, an increase of only 42%. To put it into perspective, Maca Air Color has 80% the electrical capacity of Clone yet only provided only about 60% the amount of charge. It’s worth noting that Kensington’s PowerGuard has the same capacity and got about the same result in our tests, while the only slightly larger 1250mAH Smart Battery from Third Rail Mobility provided a much better result with a 58% increase. Just like Clone, Maca Air Color has a 0.5A charging speed, half of what the iPhone can handle.

We did experience a few other issues with the cases. On both models, the Dock Connector plugs had problems the first few times we inserted the iPhone 4. The plugs have a little bit of give and don’t stand straight up, making it difficult to line the iPhone’s port up properly. We weren’t able to get the phone in place without pulling the plug towards the front of the case, an issue that was especially pronounced on Clone. We also experienced slight signal blockage issues caused by the aluminum back of Maca Air Color, but this was only in certain locations and was never more than one bar of wireless signal.

Despite their similar appearances, Mipow’s battery cases are two very different beasts, and Clone is clearly the better option. The slightly thicker case provides a substantially higher charge, and the ability to hot swap the battery with any Nokia BP-4L-style cell is appreciated. We would like see some improvements however, especially in the Dock Connector port and charging speed of the case. While the appearance isn’t as impressive as Juice Pack Air’s, Clone sells for $10 less, offers the same charging ability, and has the option of a swappable battery, all reasons that it merits a B+ rating. On the other hand, we would not recommend Maca Air Color. It’s actually more expensive and offers fewer benefits; the cool-looking back isn’t enough to save it from being underwhelming in capacity for the price. For those reasons, a C+ rating is appropriate.

Editors' Note: iLounge only reviews products in "final" form, but many companies now change their offerings - sometimes several times - after our reviews have been published.
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